A "suspected Rwandan Defense Force (RDF) mobile Surface-to-Air Missile (SAM)" was fired at a U.N observation drone last Wednesday without hitting it, the confidential report said.

"External military intelligence from France supports assessment that the suspected WZ551 6×6 IFV mobile SAM system is Rwandan," it added.

Attached to the report are two aerial images in which a six-wheeled armored vehicle is visible with a radar and missile launcher system on its roof.

The photos were taken about 70 kilometers north of the city of Goma, in rebel-held Rutshuru territory, by the targeted drone.

The UN's MONUSCO peacekeeping mission says in the document it has "no past reporting of known armed groups possessing the training, capital or resources to operate and maintain a mobile SAM system."

It added that it "indicates an escalation of conventional force conflict in eastern DRC."

Neither the United Nations nor the army of the Democratic Republic of Congo have so far commented on the incident.

Clashes have intensified recently between the M23 — among the strongest of dozens of armed groups roaming the country's troubled east — and the Congolese army.

The escalating fighting has pushed thousands of civilians to flee the town of Sake, a strategic location on the route towards Goma, capital of North Kivu province.

VOA